This book is titled "Lucid Immersion Blueprint" by Ryan Hurd. I am not allowed to post the website, so if you are curious to know what it is, look up "lucid immersion blueprint".
The webpage talks about the book and how to purchase it. It claims to help beginners and advanced lucid dreamers with dryspells and mediocre successes.

I am not sure if I want to buy it. Has anyone here every read the book? Was it as effective as it claims to be?
Thanks.

I have read it and I liked it a lot. It's scientifically grounded and rounded between its physical, mental and spiritual perspectives. It doesn't push a spiritual perspective, but is open to that side of lucid dreaming.

I would describe myself as an intermediate lucid dreamer. I had lucid dreams as a young kid, and then was caught by them again in my early 20s. Like Ryan Hurd, I have had many lucid nightmares. They took a toll on me. I was somewhat scared away from lucid dreaming and OBEs. The book helped me see that an introspective practice is vital to lucid dreaming long-term, and it gave me new ideas about how to troubleshoot.

That said, LUCID IMMERSION BLUEPRINT is also an excellent beginner's guide. It tells you everything you need to get going.

To be sure, it's made me think in a different way about my practice.

As far as it being "effective"...Yes. In my first month of doing "immersions," I had fourteen LDs (which is pretty high for me).